1. Field of the Invention
The present invention concerns a method and an apparatus for mixing liquid and paste-like substances, for example, for preparation of food in pots for large kitchens.
2. Description of the Prior Art
Pots for large kitchens of the order of 200-300 liters are still normally mixed by hand, which is very heavy work especially in the preparation of paste-like foods such as mashed potatoes, porridge, stews and the like.
There are commercial mixing apparatuses for this purpose, but none of them has been shown to function in a satisfactory way and especially not for paste-like foods of the above mentioned types.
It is known for instance from U.S. Pat. No. 3,580,550 that for mixing of viscous liquids, especially paint, one can use a propeller with two blades whose inclinations are opposite in order to realize a flow in the liquid substance. Part of the substance flows vertically upwards while another part flows vertically downwards. However, this apparatus is solely appropriate for liquid substances and cannot produce an effective mixing of paste-like substances.
It is further known from U.S. Pat. No. 2,513,254 to arrange two rotating mixers which rotate in opposite directions around the same center in order to realize mixing of a paste-like substance, for instance dough. The apparatus is very complicated, however, and is probably hard to clean.